1. Field of the Invention
The present invention relates to an apparatus having cassette loading and unloading functions and an operation mode selecting function, suitable for use in a cassette tape recorder, a video tape recorder, a digital audio tape recorder or the like.
2. Description of the Prior Art
In a cassette tape recorder, for example, a cassette loading and unloading mechanism and an operation mode selecting mechanism are conventionally provided independently of each other.
FIG. 14 is a view showing an example of a conventional cassette loading and unloading mechanism in a cassette tape recorder. Referring to FIG. 14, a conventional cassette loading and unloading mechanism will now be described.
In FIG. 14, a cassette loading and unloading cam has a cam groove 2 formed on the major surface thereof. A cylindrical portion 3 is provided around the central axis of cam 1 and a cam groove, not shown, is formed on this cylindrical portion 3. The outer circumference of the cassette loading and unloading cam 1 is coupled to a driving source 4 such as a motor so that the cassette loading and unloading cam 1 is rotated by the driving source 4.
The cam groove 2 is engaged with one end of a first oscillation link 5 having an almost L-shaped form and the other end of the link 5 is engaged with a slider pack 6 to form a sliding and turning pair. When the cassette loading and unloading cam 1 is rotated, the first oscillation link 5 moves so that the slider pack 6 slides in the vertical direction in FIG. 14. Thus, the sliding of the slider pack 6 controls the position of an inserted cassette tape in the horizontal direction (which corresponds to the vertical direction in FIG. 14).
The cam groove formed on the cylindrical portion 3 of the cam is engaged with a working end of a second oscillation link 8. The second oscillation link 8 has a relatively large surface portion and one side thereof (the lower side in FIG. 14) is engaged with a cassette holder 9 to form a turning pair. The upper right and left sides (in the drawing) of the second oscillation link 8 are rotatably supported by a base arm 10 which is partially shown. In response to the rotation of the cassette loading and unloading cam 1, the second oscillation link 8 oscillates around the portion supported by the base arm 10 so that the cassette holder 9 engaged to this turning pair is moved vertically (in the direction perpendicular to the surface of the drawing). This movement of the cassette holder 9 controls the vertical position of the cassette tape 7.
FIG. 15 is a view showing an example of a conventional operation mode selecting mechanism provided in a cassette tape recorder.
Referring to FIG. 15, the operation mode selecting mechanism comprises a driving source 11, an operation mode selecting cam 12, an oscillation link 13 and a mode plate 14. The operation mode selecting cam 12 has a major surface on which a circular cam groove 15 is formed in a manner eccentric with respect to the central axis of the cam 12. This cam groove is engaged with one end of the oscillation link 13 and the other end of the oscillation link 13 is engaged with the mode plate 14 to form a sliding pair. Thus, when the operation mode selecting cam 12 is rotated by the driving source 11, the oscillation link 13 moves with a supporting point 16 as the center so that the mode plate 14 slides vertically in FIG. 15. The mode plate 14 is moved by the oscillation link 13 so that the stopped position thereof controls the positions of a pinch roller, an idler for reel rest and the like, to select a necessary operation mode.
Conventional cassette loading and unloading mechanisms and a conventional operation mode selecting mechanisms structured respectively as described above, are of various types such as the type comprising motors 4 and 11 specially provided as the driving sources or the type using driving sources 4 and 11 from a main motor for running a cassette tape. However, in any type, a cassette loading and unloading mechanism and an operation mode selecting mechanism are structured independently. Although the above described mechanisms are shown as the mechanism in which the driving source 4 drives directly the cassette loading and unloading cam 1 or the mechanism in which the driving source 11 drives directly the operation mode selecting cam 12, the driving sources 4 and 11 in reality each includes a special motor or a main motor so that the cams 1 and 2 are rotated or moved through a complicated reduction unit or the like for decreasing the rotating force of the motor and amplifying the rotating force to a predetermined value. Accordingly, a real structure for those machanisms requires large areas for the driving sources 4 and 11 and the cams 1 and 12, and a large number of components are contained in this structure.
The below indicated table shows the driving sources for a cassette loading and unloading mechanism and an operation mode selecting mechanism in a conventional cassette tape recorder as well as the control method for those driving sources. From this table, a technical trend in the prior art concerning a cassette loading and unloading mechanism and an operation mode selecting mechanism in a cassette tape recorder or a video tape recorder can be seen.
TABLE 1 __________________________________________________________________________ Function Driving Source Control Method __________________________________________________________________________ Cassette Main motor On-off control by loading and (use with flywheel) operation of plunger unloading (+ turning on and off of power source) On-off control according to the rotating direction of motor (+ turning on and off of power source) Operation Special motor Turning on and off of mode power supply selection Main motor Notched gear + (used with flywheel) plunger Pressed gear + plunger Constant rotation Mode selection in operation according to the rotating direction of motor Large-sized Turning on and off of suction plunger power source Special motor Turning on and off of power source Mode selection according to the rotating direction of motor __________________________________________________________________________
As shown in the Table 1, a conventional cassette loading and unloading mechanism and a conventional operation mode selecting mechanism each have a structure in which a main motor is used as a driving source, or a structure in which a special motor is used as a driving source. The structure using a main motor as a driving source requires a plunger corresponding to a cassette loading and unloading mechanism and a reduction unit or the like for obtaining necessary operation force. It also requires a plunger corresponding to an operation mode selecting mechanism and a reduction unit or the like for obtaining necessary operation force. As a result, in a cassette tape recorder for example, units for the above described machanisms not associated with the running of a cassette tape need to be rotated all the time during the running of the cassette tape (in the play state) in most cases, which has the disadvantage that the running of the tape or other operation becomes unstable. In addition since, in many cases, the plunger is driven according to the two states, namely ON and OFF states of a solenoid so as to select a necessary mode, as many as three or four solenoids are required in a complicated mechanisms. In a cassette tape recorder having an automatic reversing function, for example, this causes an increase in the manufacturing cost and the size of the apparatus.
On the other hand, the structure using a special motor as a driving source requires a special motor and a special reduction unit. Accordingly, this structure has the disadvantage that the mechanism as a whole becomes large-sized and the manufacturing cost thereof is increased.
In addition, a design using a main motor for either of the mechanisms and using a special motor for the other mechanism may be considered. Even in such design, a reduction unit for obtaining necessary force is required for each mechanism and the above described problems such as a large size and an increase in the number of components cannot be avoided.